How to Manufacture Carbon Fiber Parts

Carbon fiber is one of the strongest and lightest materials on the planet. It’s used in everything from RC planes and drones to race cars and bicycles.

Carbon-fiber fabrication is an intensely hands-on process. It requires skilled workers to produce frames and parts of all shapes and sizes, whether custom or production.

Layup

Carbon fiber is a very strong and rigid material that can be crafted into finished components using various lamination methods. These include Infusion, prepreg, and wet layups. Infusion and pre-preg are more complex processes that require a mold to wrap the sheets of carbon around, while wet layups use a non-vacuum assisted process.

The wet layup method is a good way to create or repair carbon parts for applications where a mold cannot be made. Before you begin laying, it is important to thoroughly mix the resin and hardener. This will ensure the epoxy has the proper viscosity to properly adhere and cure the carbon.

You will want to prepare the surface where you are laying by scuffing it with low-grit sandpaper and wiping it clean with acetone. This will help the carbon adhere to the surface and prevent it from shifting as it cures. Once you are ready to start, apply the first layer of resin. Thoroughly paint the carbon with the resin, stopping when it looks evenly 'wetted out.'

Molding

Carbon fiber is a strong material, but it can also be difficult to cut. Cutting carbon fiber can be done with a razor blade, or if the piece is large enough a rod saw can be used to make more precise cuts. It’s best to brace the carbon fiber against something solid or another surface as you cut to prevent it from slipping out of position. The fabricator in the drone prop video mentioned above suggests using cellophane tape on either side of the cutting line to help ensure that the edges of the carbon fiber don’t unravel during the cutting process.

Once your carbon fiber composite part is finished it can be polished or clear coated to achieve a more aesthetically pleasing finish. This will protect your part from scratches and give it a deeper, richer color. Depending on the application, a paint job may be needed as well. The final step in manufacturing a carbon fiber part is to get it ‘showroom ready’ by trimming or cutting the parts where necessary to achieve a clean and professional look.

Cutting

When carbon fiber is cut, the resulting dust can be a significant health risk. It can irritate skin and eyes, and is also a potential conductor that could fry nearby electronic equipment. To avoid these risks, it is important to use proper safety precautions and work in a well-ventilated area.

Carbon fiber parts must be cut accurately to ensure they fit properly in their intended application. Using the right tools is also crucial, as lower quality saws may wear out quickly or produce uneven cuts. Rotary tools are typically more effective than hand or electric saws, and can be used to cut straight lines in carbon fiber with precision.

Marking the workpiece before cutting with tape helps achieve accurate, clean cuts. It’s also a good idea to use a silver permanent marker combined with tape for extra precision. Once the part has been cut, it can be finished by polishing or clear coating. Each of these processes deserves their own blog post, but both can be achieved in the home with a few simple products.

Finishing

The final stage is to apply a clear coat, which is both cosmetic and protects the carbon fiber from UV degradation. The process is fairly straightforward, but takes some finesse to get it right.

It’s important to apply enough resin, but also not too much. Too much and the carbon fiber can pull away from the surface, leaving air bubbles and a rough texture. It’s also important to take your time. The ideal cure window for epoxy is short and it can be tricky to conform the carbon fiber to curves and sharp corners.

Polishing can be a great way to give your carbon fiber parts a deep, glossy finish that really showcases the beauty of carbon. This can be a time-consuming step, but the results are worth it. The best way to test a finished carbon fiber part is to knock it with your indicator finger knuckle. If it sounds like a piece of fiberglass, you’re dealing with fake.